Vapor-liquid distribution method and apparatus for the conversion of hydrocarbons



16, 1965 J. H. BALLARD ETAL 3,213,249

VAPOR-LIQUID DISTRIBUTION METHOD AND APPARATUS FOR THE CONVERSION OF HYDROCARBONS Filed March 30, 1964 4 Sheets-Sheet 1 1NVENTOR5 /a///v 4LLARD ./a/-//v 5. 16 01/55, JR,

4770A /VEY Nov. 16, 1965 J. H. BALLARD ETAL 3,218,249 STRIBUTION METHOD AND APPARATUS FOR THE VAPOR-LIQUID DI CONVERSION OF HYDROCARBONS 4 Sheets-Sheet 2 Filed March 30, 1964 Y 0 we w T A. 5 p mu m V4 N T WJH .A #5 u mm W Y N 1965 J. H. BALLARD ETAL 3,218,249

VAPOR-LIQUID DISTRIBUTION METHOD AND APPARATUS FOR THE CONVERSION OF HYDROCARBONS Filed March 50, 1964 4 Sheets-Sheet 3 400 500 /200 /000 2000 2400 2500 3200 3600 4000 4400 7-0724 4/? F40/4/ 70 TWO 0/5506; 50/9 INVENTORS Jay/v H. 541.44%: JOHN E. ///A/E5, JR.

Nov. 16, 1965 J. H. BALLARD ETAL 3,218,249

VAPOR-LIQUID DISTRIBUTION METHOD AND APPARATUS FOR THE CONVERSION OF HYDROCARBONS 4 Sheets-Sheet 4 Filed March 50, 1964 z/qw/p- VAPOR INVENTORS JOHN/9, 5444/4/7 United States Patent VAPOR-LIQUID DISTRIBUTION METHOD AND APPARATUS FOR THE CONVERSION OF HYDROCARBGNS John H. Ballard, Whittier, and John E. Hines, In, Newport Beach, Calif., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California Filed Mar. 30, 1964, Ser. No. 355,870 21 Claims. (Cl. 208-108) This application is a continuation-in-part of application Serial No. 201,603, filed June 11, 1962, and now abandoned.

This invention relates generally to means and methods for distributing a vapor-liquid mixed phase feed to a contacting zone in a reactor or cont-actor, and to means and methods for effecting heat exchange between vapor and liquid phase in a contacting vessel. More particularly, the invention relates to a new and improved method and apparatus for uniform-1y distributing mixed phases to a granular solids contacting zone in a downfiow catalytic contactor such as a hydrodesulfurization, hydrocracking, or other catalytic reactor.

One embodiment of the feed distribution means of this invention comprises a substantially horizontal distribution tray mounted above a contacting Zone in a reactor or equivalent contacting vessel, said tray having cap and downcomer or conduit means through which the vapor and liquid feed materials are distributed onto a bed of contact material or to a subsequent contacting zone below. The cap and downcomer conduit means may resemble, in size and arrangement, bubble caps of the type commonly used in distillation columns, but they serve a far different function in our invention that do distillation bubble caps. In our invention, a vapor-liquid mixed phase feed is introduced to the distribution tray by means of a sparger, perforated tray or other device whereupon the distribution tray, in turn, causes distribution of the mixed phase feed uniformly over the contacting zone. We have discovered that feeding vapor-liquid mixtures onto contact materials through our cap and downcomer feed distribution conduits results in a number of unexpected advantages over the use of previously known methods for accomplishing the same result.

Among the most important of the various commercial processes are those involving the physical or chemical treatment of hydrocarbons and other organic materials with bodies of granular contact material. Many of these processes involve the contacting of two-phase mixtures of liquids and vapors with said contacting materials, and the introduction of such mixtures into a bed of granular contact material in a uniformly distributed manner is difficult of achievement. Heretofore such vapor-liquid feed materials have been fed to beds of contact material in reactors through distribution trays with a relatively large number of outlet nipples, overflow weirs, or the like, the feed mixture being introduced into the reactor above the distribution tray in such fashion that the liquid collects in a pool or reservoir on the tray from whence it flows to the bed of contact material over the rims of the outlet nipples, or the like. Outlet nipples typical of this type of feed arrangement are described and shown in US. 2,898,- 292 to Halik et al. The overflow rims of the Halik et al. outlet nipples are V-notched to facilitate more even overfiow of the liquid, the use of such V-notches (or serrations, slits, etc) being quite common in the art. The vapor constituent of the feed mixture is forced through the outlet nipples and then through the bed of contact material by the operating pressure drops within the reactor.

There are several serious disadvantages inherent in the use of the outlet nipples of Halik et al. or equivalent over- "ice flow devices. For one thing, the methods of fabrication normally employed in the construction of reactors are not sufficiently precise to assure an absence of irregularities (minor differences in outlet nipple elevation, tilting of nipples, etc.) in reactor distribution trays. Also, the operating conditions within reactors are frequently such as to bring about distribution tray warping, thus contributing to even more irregularities. As a result, some of the higher outlets will invariably exhibit little or no overflow of liquid feed. To emphasize the point, the low liquid flow rates encountered in typical reactors coupled with the necessary large numer of outlet nipples (sometimes referred to as distribution points) results in liquid heights in V-notch overflow weirs conventionally in the order of to /s-inch. From this it is apparent that small variations in elevation between outlet nipples give wide variations in liquid flow. Also as a result of the inherent irregularities in such trays, liquid feeds have a tendency to channel down the inner surfaces of the outlet nipples and thus strike the catalyst bed below in relatively thin streams which bury themselves deep in the bed before spreading laterally to any significant extent.

It is accordingly a principal object of the present invention to provide improved means and methods for the contacting and/or distribution of vapor-liquid mixed phases in contacting vessels.

It is a further principal object of our invention to provide means of feeding vapor-liquid mixed phase feeds to one or more beds of granular solids contacting material in reactors whereby substantially even distribution of the feed materials throughout said beds is readily accomplished.

It is another object of the invention to provide such means whereby channeling of the liquid phase of the feed through the upper granular solids bed layers is substantially eliminated.

It is still another object of the invention to provide such feed distribution means whereby greatly improved admixture of the vapor and liquid phases of the feed material at their point of introduction into the solids contacting zone, and thereafter within said zone, is achieved.

It is a further object of the invention to provide a means of heat interchange between a liquid feed portion and a vapor feed portion to a reaction system, where the vapor and liquid are at different temperatures, so that the liquid and vapor entering a subsequent contacting zone approach the same temperature.

Other objects and advantages of our invention will be apparent to those skilled in the art as the description of the invention proceeds.

We have found that the foregoing objectives and their attendant advantages can be realized by substituting our bubble cap feed arrangement for the conventional outlet nipple arrangement, and the above-noted disadvantages of prior art devices and methods are greatly minimized or eliminated. Thus, by utilizing the teachings of this invention, much more even distribution of the liquid portion of a liquid-vapor feed material through beds of contact material is achieved. Our bubble cap feed arrangement, as will be readily apparent from the complete description of our invention to follow, results in much improved admixture of the vapor and liquid reactants, both at their point of introduction into the contacting zone and thereafter in their travel through the bed of contact material. For reasons indicated above, and in the description to follow, the use of the feed distributing means of this invention leads to higher feed conversions and more efficient utilization of reaction contact materials.

It has also been found that our vapor-liquid distribution method is an effective heat transfer device. In a reaction system wherein a quench gas is fed to the inlet of a contacting Zone together with hot material entering the zone, an interchange of heat between the cold quench gas and hot feed is required so that the vapor and liquid portions of the feed approach the same temperature on entering the granular solids contacting Zone. Similar heat exchange would be necessitated if the gas portion was at substantially higher temperatures than the liquid portion of the feed. This heat interchange can be effectively achieved by direct contact of the liquid and the vapor in our distribution device.

The invention will be more readily understood by reference to the accompanying drawings of which:

FIGURE 1 is an elevation view, partly in section, of a reactor incorporating the feed distribution means of this invention;

FIGURE 2 is an enlarged elevation view, mostly in section, of a cap and downcomer feed conduit according to this invention, taken along line 22 of FIGURE 1;

FIGURE 3 is a cross-sectional plan view of the cap and downcomer assembly taken along line 33 of FIG- URE 2;

FIGURE 4 is an enlarged partial cross-section of the reactor of FIGURE 1, showing a plan view of one quadrant of the distribution tray with cap and downcomer fittings, taken along line 44 of FIGURE 1;

FIGURES 5, 6, and 7 show several cap designs suitable for use in our invention;

FIGURE 8 is a graph of data showing the levelling effect of our cap and downcomer distribution means on liquid flow rates through individual distribution tray outlets;

FIGURE 9 is a graph of data showing the damping effect of our cap and downcomer distribution means on liquid flow rate variations caused by vapor flow fluctuations through downcomers of different heights and the effect of vapor rate on liquid distribution;

FIGURE 10 is an elevation view of a portion of a reactor, in cross-section, incorporating another embodiment of a distribution means according to this invention which is particularly adaptable to the inter-mixing of a quench gas with liquid-vapor entering an intermediate contacting zone;

FIGURE 11 is a cross-sectional plan view of the quench deck installed above the distribution tray in the embodiment of FIGURE 10 taken along the line 1111 thereof;

FIGURE 12 is a plan view of the perforated tray installed above the distribution tray in the embodiment of FIGURE 10 taken along the line 1212 thereof; and

FIGURE 13 shows the detail of another embodiment of a riser found to give superior distribution of the liquid portion of the feed.

It is to be understood that although the mixed phase feed distribution method and apparatus of this invention are broadly applicable to any contacting system, and thus to any reactant downflow contacting system, they are particularly useful in catalytic reaction systems. The method and apparatus are specifically applicable for use in catalytic hydrodesulfurization and hydrocracking reactors, but they can also be used to conduct any contacting or treatment in which a portion of the feed is in liquid phase and the balance in vapor phase, such as in catalytic polymerization, isomerization, etc., of petroleum hydrocarbons, catalytic hydrogenation of liquid coal extracts, catalytic hydrogenation of aromatic compounds such as the conversion of benzene to cyclohexane, catalytic oxidation, catalytic chlorination, and the like.

Referring now to FIGURE 1, the apparatus there shown consists essentially of a reactant downflow catalytic reactor with its various internal parts. Cylindrical vessel 2, having a top 4 and a bottom 6, is usually constructed of corrosion resistant metal or an equivalent material, such as stainless steel, ceramic, or the like, and is normally insulated internally or externally for operation at elevated temperatures. While the outer shell of the reactor is substantially cylindrical in the preferred form of our apparatus, it can also be of a non-cylindrical shape if desired. Outlet conduit 8 is provided in bottom 6. Vessel top 4 is provided with access conduit 10 for convenience in filling vessel 2 with catalyst, and for routine maintenance. A foraminate, cone-shaped cylindrical grating 12, located immediately above outlet conduit 8, is provided as a barrier to prevent escape of the solids within vessel 2 through outlet 8 while at the same time permitting fluid product to discharge therethrough. Feed inlet conduit 14 communicates with a sparger 16 which comprises a closed-end pipe with two identical radial slits 17 in its upper portion, of which only one shows on the drawing, the other being hidden from view. The vapor-liquid feed is introduced into the top of vessel 2 through the slits in the sparger which are so positioned that an end view of the sparger in operation would reveal the feed issuing therefrom in two sheet-like jets, first diverging in a roughly V-shaped pattern and then rapidly disintegrating so that the liquid is somewhat distributed within the vessel. Additional vapor can be introduced into vessel 2 through access conduit 10 if desired.

The foregoing features are conventional in a great many catalytic reactors. The improvement of our invention comprises a novel feed distribution system which takes the form of a transverse partition, or distribution tray, 18, fitted with caps and downcomers such as shown at 7, 7a, and 7b on the drawing. For ease of illustration, the center row of caps and down-comers on distribution tray 18, which would be bisected by the section plane employed for the FIGURE 1 view, is omitted and the rearwardly adjacent row is shown in elevation (except for hidden portions passing through tray 18) instead. Thus, instead of 10 downcomers (the number in the center row, as evident from FIGURE 4), only 9 are shown, a representative three of which are symbolized as 7, 7a, and 7b on the drawing. Distribution tray 18 is securely mounted substantially horizontally within vessel 2 by a circumferential angle 19 firmly attached to the walls of vessel 2, or by other conventional supports such as angle sections, channels, brackets, welding or the like. Tray 18 is substantially vapor and liquid-tight, except for the downcomer conduit openings.

Below tray 18, and spaced apart therefrom in vessel 2, is the contacting zone of the reactor in which is disposed a bed of granular catalyst material 102, .under a layer of chemically inert spherical pellets 100. In reactors of conventional size and design for hydrodesulfurization or like purposes, the inert pellets are preferably ceramic balls made of fused alumina or equivalent material interposed between the distributor tray and the catalyst bed, forming a layer, preferably from about 3 to about 6 inches in depth. The chemically inert pellets act to improve the uniformity of distribution of the feed from distribution tray 18 and tend to prevent disruption of the upper surface of the catalyst bed. The character of the material in catalyst bed 102 will depend upon the nature of the reaction taking place in the reactor. Thus, in the case of hyd'rodesulfurization, a typical catalyst will consist of Ax-inch pelleted cobalt-molybdate hydrodesulfurization catalyst. Disposed below catalyst bed 102 is bed 106, which is another bed of inert ceramic spheres, or the like, surrounding and abutting against grating 12. The layer of inert spheres is optional and may be eliminated completely or replaced by an equivalent, or other, volume of catalyst material if desired.

There are many reactor design variations within the scope of our invention and reactors suitable for our purpose can differ substantially in non-critical aspects from the FIGURE 1 embodiment. Such reactors can, for example contain two or more distribution tray-catalyst bed combinations, or units, which can be arranged in series or parallel relationship. It is not essential that the catalyst beds in the reactors of this invention have adjacent layers of inert materials such as inert spheres 100 and 106 of FIGURE 1. The catalyst beds, whether or not covered by a layer of inert spheres or the like, may, if desired, have a plurality of foraminate baskets embedded therein in the manner shown in copending US. patent application Serial No. 1,505 to Young et al., which has matured into US. Patent No. 3,112,256, issued November 26, 1963. The baskets may be filled with inert ceramic particle-form material or not and they serve the purpose of providing more uniform distribution of the mixed phase reaction feeds throughout the catalyst bed while, at the same time, removing foreign matter from the feed materials which might otherwise plug the bed. These functions, as well as others served by the baskets, are set forth in greater detail in the aforesaid patent.

Turning now to FIGURES 2 and 3, it will be noted that the downcomer 26 and cap 23 are fastened together by means of a bolt 20, a nut 22, a spacer 23, and a strap 24. Bolt 20 passes through a hole in the center of the end closure 30 of cap 23 and a hole in strap 24 aligned therewith in such fashion as to affix cap 23 in proper spaced relation to downcomer 26. Nut 22 fastens the whole assembly together. Strap 24 is a relatively narrow strip of metal, or other suitable material, fastened diametrically across the upper opening of downcomer 26 by welding or other means. The illustrated arrangement is merely one of the possible ways of fastening the caps and downcomers of this invention together. Many alternative ways of accomplishing the same result will readily occur to those skilled in the art, all of which, of course, fall within the scope of our invention. Thus, it is within the scope of the invention to have no physical connection at all between cap and downcomer, so long as they are properly positioned for each to fulfill its intended purpose. Downcomer 26 projects through tray 13 and is fastened thereto by welding as indicated at 32, by suitably forming the riser to secure it in position on the tray as shown in FIGURE 13, or by other suitable means. The materials from which all of the parts here involved are made should, for best results, be substantially non-corrosive with respect to the feed and other materials present in the reactor. Preferable materials from which to fabricate such parts are steel, ceramics, plastics, etc.

We have discovered that improved results are achieved when the bottom rim of cap 28 is slotted equidistantly around its periphery as illustrated at 34 and 34a, of FIGURE 2, but cap 28 can also be left unslotted. The depth of the slots should preferably be from about A; to about A2 of the depth of the cap itself and the width of the slots from about 4 to about /5 of the cap crosssectional diameter. However, another even more suitbale operating range of slot widths is from about to about A; of the cap cross-section diameter. All slots are preferably, but not necessarily, of the same size and shape. Other types of slots or notches besides those shown, such as V-notches, can be used if desired. Some typical slots are illustrated in FIGURES 5, 6 and 7. No matter which slot is utilized, the top of the slot should be maintained below the bottom of the upper rim of the downcomer. Although not essential, good practice would be to maintain a clearance of at least A-inch between the top of the slot and the top of the riser. The top of downcomer 26 can be slotted in the manner shown at 36, or left unslotted, as desired. Any feasible number of such slots can be employed. For example, we have successfully employed two diametrically opposed slots. Although the downcomer slots can be of any design, it is not necessary that they be more than about /2-inch in depth as their function is merely to restrict the flow of liquid over the rim of the downcomer in order to achieve a balancing of liquid flow. The bottom of the downcomer slots should be maintained above the top of the cap slot.

The number of downcomers required for our purpose is variable, and can be the same as, greater than, or fewer than the number of corresponding outlet conduits in distribution trays heretofore known to the art. However, as will be hereinafter explained, the liquid discharge from our downcomers is not in discrete thin stream form, but is entrained in the vapor discharge to form a mixture of vapor and liquid which issues from each downcomer in an exit pattern substantially co-extensive in circumference with the downcomer cross-section thereby, with appropriately located downcomers, achieving substantially uniform distribution over a cross-section of the vessel. Accordingly, another advantage of our invention, not heretofore mentioned, is the ability by its use to obtain better feed distribution over the surface of the catalyst bed with fewer downcomer conduits than has previously been possible. The optimum number of downcomers for any given purpose will depend on many factors, the most obvious of which is the size of the reactor. Other contributing factors are the feed rate to the reactor and the proportion of the feed remaining in the liquid phase. In general, the design of the distribution tray will provide the proper number of downcomer outlets to assure optimum liquid level on the tray, and concomitant optimization of gas flow through each outlet for a given feed rate and reactor size. Usually, the downcomer will be from about 3 to about 6 inches in cross-sectional diameter, although downcomers as small as 1% inches, or less, or larger than 6 inches may be employed.

It is not necessary that the downcomers extend through the tray and project into the catalyst chamber below as shown in FIGURE 2, but there is no objection to this and in fact such projection is preferable in most instances. Where the downcomers do project in such fashion, however, they should preferably extend only a short distance below the distribution tray. Too great a distance mitigates against good dispersion of the feed onto the catalyst bed surface and too short a distance creates the possibility of liquid migration via the outer peripheries of the downcomer extensions to the under surface of the distribution tray and even to other downcomers before dropping onto the catalyst bed.

A preferred cap and riser design is shown in FIGURE 13, wherein is seen cap 300 mounted on riser 362. Riser 302, corresponding to riser 26 in FIGURE 2, is formed to provide protruding section 304. Riser 302 is inserted through downcomer hole 306 in tray 18 so that protruding section 304 rests on the tray. Riser 302 is then rolled to form flared section 308 which firmly secures the riser to the tray without welding or other means. We have found that the liquid tends to flow down the riser wall, particularly at lower vapor rates, and that flared section 3th; causes the liquid to be disengaged from the riser in a conical pattern thereby achieving greater distribution of the liquid over the cross-section of the vessel. The extent to which riser 302 is flared in part determines the flow pattern of the liquid eflluent discharged from the riser. The riser tip may be flared approximately degrees from the axis of the riser so that the riser is rolled against the bottom of tray 18 without loss of effectiveness as a fastening device. However, optimum flow patterns may not be achieved with such a wide flare. Satisfactory flow patterns can be obtained at flare angles between about 10 degrees and about 70 degrees from the axis of the riser, with a preferred range being between about 20 degrees and about 60 degrees. Angle clips 310, usually three in number, are attached to riser 302 by welding, or other convenient means, and serve as a mounting for cap 300. Holddown clamp 312 is attached to support means 314, which in turn is fastened to angle clips 310. Cap 300 is positioned on riser 302 with holddown clamp 312 being inserted through a slot in the top of cap 300 out therein for that purpose. Cap 300 is fastened in position by a wedge, not shown, which is inserted through slot 316 in holddown clamp 312. Centering lugs 318, more fully described hereafter, maintain cap 300 centered over riser 302.

Feed should be introduced to the distribution tray in a more or less uniform manner and without excessive velocity head or impingement on the bubble caps. There are a number of acceptable means of introducing liquid and vapor feed to the distribution tray. As disclosed above, one such conventional method is with a sparger. This device is particularly suitable for two-phase systems Where equilibrium conditions have been approached prior to the material reaching the distribution tray. It is frequently the case, however, that a cold gaseous material, or quench gas, will be introduced with liquid and vapor influent to a contacting zone for temperature control or other reason. In such cases different types of devices can be installed above the distribution tray to pre-mix the feed and quench gas and to achieve more or less even distribution of the feed and gas to the distribution tray. Such devices which can be used include, but are not limited to, solid staggered partial bafi'les, perforated trays and partially perforated trays.

One effective device for pre-mixing and distributing a liquid-vapor influent to a contacting zone and a quench gas is shown in FIGURES 10, 11, and 12. This device is particularly suitable where the liquid-vapor influent is the etfiuent of a contacting zone immediately above passing to a lower contacting zone. The device described herein may thus be installed in the top of a vessel for pre-mixing a quench gas and a vapor-liquid feed to an upper contacting zone, or it may be installed intermediate to two contacting zones within the vessel. Referring to FIGURE 10, a liquid-vapor influent passes downwardly through vessel 200 to contacting zone 102. As mentioned above, this material may be either a liquid-vapor feed to vessel 200 or a liquidvapor effluent from a contacting zone above. Quench gas is introduced into an intermediate zone between two adjacent contacting zones at a point in the center of vessel 200 by means of nozzle 202 and internal pipe 204. Quench deck 206 comprises a solid tray across the crosssection of Vessel 200, removably attached to the vessel wall around the periphery of deck 206 by means capable of a substantially leak-free seal. Two relatively large diameter holes, conduits 208, not shown in the section view of FIGURE 10, open into box 210 and provide the only means of communication from the top section of vessel 200 through deck 206. Quench box 210 is positioned immediately below deck 206 and is fixedly attached thereto by welding, or other means. Quench box 210 is usually located concentric to deck 206 and comprises bottom and side members, quench deck 206 serving as a top member to enclose the box. The inlet to box 210 is through conduits 208 and the only outlet is through conduits 212 located in the bottom of box 210 approximately 90 degrees removed from conduits 208. Liquid-vapor influent and quench gas entering the upper section of vessel 200 divide into two streams of more or less similar compositions and flow quanities. Each of these streams passes downwardly through one of conduits 208 into quench box 210. On entering quench box 210, each of the two streams flowing through conduits 208 divide into two streams of approximately equal composition and flow quantities which are combined with a similar portion of the stream passing through opposite conduit 208. Each of the recombined streams passes downwardly through conduits 212 to perforated tray 214 below. Orientation of conduits 212 and 214 are illustrated in FIGURE 11, which is a plan view of quench deck 206 showing conduits 208 and, in outline, the location of quench box 210 and conduits 212. Although the illustrated embodiment employs two quench box inlet openings and two outlet openings, our invention is not so limited. Any number of quench deck openings may be employed, usually located sub-' stantially equidistant from the center axis of the vessel, and spaced substantially equidistant from the center axis. Similarly, any number of outlet openings may be employed, these openings also being usually located substantially equidistant about the center axis of the vessel and substantially uniformly offset about the center axis from the openings in the quench deck. The purpose of offsetting the outlet openings is so liquid will not pass directly through both the inlet openings and the outlet openings without impinging on the bottom member of the quench box thereby causing a change in flow direction. We have found that the embodiment employing two quench deck openings and two quench box outlet openings is preferred because superior distribution is achieved. Should channeling occur above the quench deck, downflowing liquid from any portion of the vessel cross-section is effectively redistributed over the vessel cross-section by passage through the apparatus described above and illustrated in FIGURES 10 and 11.

Referring again to FIGURE 10, perforated tray 214 extends across the cross-section of vessel 200 below quench deck 206 and quench box 210, and is removably attached to vessel 200 around the periphery of the tray. One orientation of perforations 216 is shown in FIGURE 12, a plan view of tray 214. Tray 214 has perforations 216 uniformly distributed thereover, except in the area im mediately beneath conduits 212 indicated at 230. It should be noted that any convenient orientation, size, shape, and number of perforations may be employed, the particular design to be based on established chemical engineering practices. Tray 214 functions to prevent localized impingement of the downflowing material on distributor tray 18. Distributor tray 18, containing bubble cap and riser assemblies such as those typically illustrated at 7, 7a, and 7b, is located below perforated tray 21.4. Tray 18 is constructed and operated in accordance With the foregoing method and as shown in FIGURES 1, 2, 3, 4, 5, 6, 7, and 13. Other modifications of apparatus can be used to reduce the velocity head of the entering fluid and such devices are within the scope of our invention.

It is preferred that the downcomer elevations be as nearly identical as possible to achieve optimum equality of liquid flow therethrough, but considerable variation in elevation is permissible as will presently be shown. The caps over the downcomers, i.e., the distribution caps, can vary widely in size and design. However, for most practical purposes the caps should be of cylindrical design with an outside cross-sectional diameter of from about 4 /2 to about 9 inches and a vertical dimension roughly equivalent thereto. It is preferable in some applications to use caps of smaller size, down to about 2 inches or less. It is not necessary, however, that either the downcomers or caps be of cylindrical shape, and they may be of square, rectangular, triangular, or other cross-sectional configuration if desired. The lower rims of the distribution caps can be adjusted to any level above the distribution tray so long as the flow of gas through the downcomers is not sealed off; a reasonable range being from a level corresponding to practically no distance above the tray to a distance of about one foot ther eabove. It should be pointed out, however, that the liquid on the distribution tray provides a settling zone for the accumulation of sludges, particles of scale and other solid materials present in the system. For obvious reasons, it is preferably that these sludges be spread as uniformly as possible over the surface of the distribution tray and for this reason it is normally preferable to avoid close tolerances between the tray and the distribution cap rims.

FIGURE 4 is a plan view of one quadrant of distribution tray 18 showing the disposition of caps and downcomers thereon. As will be noted, the downcomers are uniformly distributed over the surface of the tray. The illustrated plan is merely representative and there are, of course, many alternative downcomer arrangements. One of the design considerations for tray 18 is that there be sufiicient downcomer conduit area to assure a relatively small pressure drop across the tray. The usual commercial practice is to construct the quench deck, perforated trays and distribution tray with removable sections to permit access to the vessel for catalyst loading and maintenance. The joints thus created, if properly installed, have no effect on the operation of these trays.

In operating a reactor in accordance with this invention, a mixed phase vapor-liquid feed is introduced into the upper portion thereof through inlet conduit 14 and sparger 16, which distributes the liquid onto tray 18 with a minimum of splashing and erosion. The liquid phase, disengaged from the vapor phase by gravity, fills up on tray 18 to a level below the slot depth in the downcomer caps, such level being determined primarily by the gas flow rate per cap. It is, of course, necessary that some of the slot openings be exposed above the liquid surface to permit the passage of vapor therethrough. Where the caps have no slots, the liquid level on the tray will be below the bottom rims of the caps for the same reason. Where unslotted caps are used, clearance between the bottom rim and the tray must be maintained to accommodate the passage of gas and liquid thereunder.

The pressure drop through the distribution tray in the reactor, which is normally quite small (although operating pressures themselves can vary substantially so long as the vapor phase of the feed remains unliquifled), forces the feed vapor under the downcomer caps, either through the slots are around the bottom rims thereof as indicated above, from whence it flows upwardly through the annulus between the downcomer cap and the downcomer, reverses direction and thence flows downwardly through the downcomers into the contacting zone. The vapor, because of the forces acting on it as a result of being fed to the reactor under pressure and then forced into the contacting zone through the tortuous cap and downcomer paths, is in constant turbulence as it contacts the liquid in the reservoir on the distribution tray in the vicinity of the downcomers. For this reason, alone or possibly in conjunction with other reasons not clearly understood, the vapor entrains liquid with it as it passes through the cap slots or under the downcomer cap and transports it through the downcomers from whence it is discharged into the contacting zone in the manner hereinbefore described. The liquid on the distribution tray seeks its own equilibrium level, as dictated by the design of the apparatus, and it is thus not necessary for operability to achieve optimum design efficiency of the distribution tray. The reactor will be operative so long as the liquid level on the tray does not seal off all openings in the downcomer caps. As mentioned above, all of the joints on the tray should be sealed so that all of the liquid and vapor passes through the downcomer conduits, except any small controlled quantity of liquid which might flow through weepholes in the tray for the purpose of emptying the tray on shutdown.

As previously indicated, differences in elevation between conventional distribution tray outlet nipples of the type heretofore known are reflected in substantial disparity of liquid flow rates therethrough and, in some cases, by complete absence of flow through the outlets of higher elevation. Also as previously indicated, the use of our cap and downcomer feed distribution means tends to obviate differences in liquid flow rates which would otherwise result from elevation discrepancies. The salutary effect of our invention in this respect is attributable to physical phenomena inherent in its mode of operation. Thus, in the sense that by its nature the method of our invention overcomes the adverse effect of outlet nipple elevation discrepancies heretofore experienced in feed distribution methods, the method can be said to be selfcompensating with respect to such discrepancies. While not wishing to be bound by any theory in explanation of the manner in which downcomer elevation differences are compensated for in the practice of our invention, it is believed that this aspect of the invention can be explained as follows: assume that two cap and downcomer outlets of identical design, size and cap-downcomer spacing but of different downcomer elevations are disposed in a reactor being operated in accordance with the method of our invention. Under these circumstances it is evident that the vent openings exposed over the liquid level on the distribution tray are larger in the cap of higher elevation than in the other cap. This being so, it follows that more vapor will pass through the larger openings and more li uid is picked up thereby. However, the vapor with the greater liquid load has a longer way to lift since the overflow weir of the downcomer through which it flows is higher above the liquid surface, and it therefore loses a greater percentage of that load to gravity before delivery to the downcomer than does the vapor passing through the lower downcomer. It will thus be seen that there are two opposing agencies at work which operate in such fashion as to level out liquid flow rates between the two downcomers.

Observations of the distribution tray in operation have disclosed that on occasion the bubble caps will not be positioned so that their centers coincide with the centers of the vertical risers, thus resulting in some slight maldistribution. Such improper positioning can be easily prevented by installing small centering lugs inside the cap to maintain the cap in proper position with respect to the riser. Three such lugs spaced degrees apart around the inside periphery of the cap and of sufficient size to just clear the outside diameter of the riser will properly center a cylindrical cap over a cylindrical riser. Such lugs are seen at 318 in FIGURE 13. Other modifications can be adapted to properly position non-cylindrical caps.

The feed temperature to a catalytic reactor or other solids contacting zone is frequently cooled by admixture of a cold quench gas with the reactor feed. In a twophase reactor, the introduction of the cold quench gas results in a tendency for super cooling of the gaseous or vaporous phase and only limited cooling of the liquid. Thus, as the feed mixture conventionally enters the solids contacting zone, the liquid portion may be substantially higher in temperature than the gaseous portion. Some form of improved heat exchange is necessary to achieve the desired condition wherein the liquid and gaseous portions of the feed are at substantially the same temperature. Such heat transfer is rendered difficult by the concurrent flow conditions of liquid and vapor phases through the reactor. We have found that our vapor-liquid distribution tray promotes the interchange of heat between the vapor and liquid portions of the feed to the extent that the temperature difference between phases is reduced to at least about 15 percent of its initial value. Further, heat transfer may be elfected in the sparger, in the quench box, on the perforated tray or other feed distribution device, and in the Alundum ball section of the reactor. Thus, overall heat transfer is greater than that obtained by means of the distribution tray alone.

Example I This example demonstrates the inequality of liquid flow through outlet nipples of the conventional type, even when special efforts of a kind not incident to the normal fabrication and installation of commercial units are made to avoid nipple irregularities.

A 30-inch diameter mockup of a catalytic reactor equipped with a high capacity blower for gas feeding purposes, a pump for liquid circulation, and orifices for flow measurements was employed in carrying out the work of this example. The blower gave a head of 2 psi. at low flow rates, and flow rates as high as 1,300 s.c.f./ min. at zero head. The pump also had a high head and capacity; suitably sized orifice plates were used where necessary in the system. Flow was set by hand using a metering valve.

For purposes of this example, a 30-inch diameter distribution tray having 19 identical distributing risers was constructed and positioned horizontally within the aforesaid mockup. The risers were approximately 6-inch lengths cut from a 3-inch pipe. They were set into the tray, projecting upward, at a spacing of about 6 inches and on an approximate hexagonal layout. vThe risers each had two As-inch by l-inch sawcuts in the upper rim. The mockup apparatus was set up with the tray level and with the 19 risers carefully adjusted to a uniform elevation. The overall deviation of the risers from level did not exceed -inch, the deviation being even less on adjacent risers. As indicated previously, such an exact installation could not be expected commercially. The two As-inch slots were cut in the risers to aid in giving even more uniform flow rates than would otherwise be possible. At the flow rates tested, which approximated the rates in commercial units, the liquid flowed only through the bottom portions of the slots.

The vapor-liquid system tested in this example was an air-water system. The water was introduced onto the distribution tray through a sparger consisting of a 24-inch length of l /z-inch Schedule 40 pipe with many -inch holes tapped through its walls. The water squirted out through the holes and rained down upon the risers at random. To prevent water from short-circuiting the tray and passing directly through the risers, each riser was provided with a covering plate, or hat. In operation, the risers were surrounded by a reservoir of water which overflowed through the slots in their upper ends. The air feed was pumped into the top of the mockup enclosure behind a bafile to prevent impingement upon the tray, risers, liquid reservoir, etc.

In obtaining the results of this example, the mockup unit was operated at a water flow rate of 1.52 g.p.m. and an air feed rate of 350 s.c.f./rn. The water, after building to the etfective weir level on the tray, passed down through the risers along with the accompanying air. The water from each riser was disengaged from the air, collected and weighed separately. To accomplish this, the risers were provided with an inner sleeve whereby the water entered the annulus between the riser and sleeve and passed to an external weighing receiver. Most of the air passed through the sleeve and was vented to the atmosphere. The water flow through each riser was measured and the ratio of water flow therethrough to the average of all risers was calculated and plotted. The resulting data appear below in tabular form and on FIGURE 8 in graphical form. It will be noted that the calculated flow ratios vary widely, from 0.40 to 1.82, indicating great inequality of flow through the carefully levelled risers.

TABLE 1 Water flow/ water fiow Riser No.: average of all risers 1 1.44

Example 11 This example was similar to Example I and was performed with the same apparatus except that here the risers in the distribution tray were fitted with metal caps, roughly 4 /2 by 4 /z-inches in size, in accordance with the teachings of this invention. Each cap was slotted around its lower rim with 14 slots of l /z-inch by fit-inch dimensions.

Water and air were fed to the thus modified mockup at substantially the same rates as employed for the Example I procedure (water rate: 1.46 g.p.m.) and the water from each riser was collected and weighed in the manner described above. The ratio of water fiow through each riser to the average flow of all risers was calculated. The resulting data are tabulated below in Tab-1e 2, and plotted in FIGURE 8.

TABLE 2 A comparison of the above data with those of Example I shows the remarkable extent to which the caps equalized the liquid flow through the risers. Thus, in the case of riser No. 2 where the ratio of flow to the average flow rate was 1.82 in Example I, the equivalent ratio was 1.13 here. To the opposite extreme, riser No. 12 had a ratio of 0.40 in Example I whereas the ratio for the present example was 0.91.

Example III This example illustrates the ability of the cap and downcomer distribution tray outlets of our invention to compensate for differences in elevation between downcomers during gas flow rate fluctuations and thus reduce flow rate unbalance between misaligned downcomers.

The mockup with the capped riser modification of EX- ample II, with all but two of the risers blocked, was employed for this example. Air and Water were fed to the mockup in the same manner as in Examples I and II, except that the air flow was altered stepwise, over a fairly wide range, for each of three runs. The water flow rate was maintained at a constant value (0.5 g.p.m.) throughout all of the runs. The runs differed from each other in riser elevation discrepancies. Thus, one run (taken as the standard) was conducted with the two risers at the same elevation, a second run with a fit-inch difference in riser elevation, and the third run with a Aa-inch riser elevation diflerence. It was a simple matter to adjust the risers to desired elevation misalignments since each was fastened to the tray by a collar and a set screw arrangement which was itself removably secured to the tray.

Data from this example are plotted in FIGURE 9 of the accompanying drawings which graphically illustrates the minimal effect of the air flow changes on the water flow rates through the two risers. Thus, it will be noted that in the case of the %-inch misalignment, the fraction of water passing through the lower riser varied only from about 0.4 to about 0.6 of the total flow, between air flow rates of about 1,800 and about 3,600 s.c.f./h. In the case of At-inch misalignment, the flow of water through the lower riser varied only from about 0.43 to about 0.55 of the total flow between air flow rates of 1,200 and 3,600 s.c.f./h. With respect to the run with the two risers supposedly at the same elevation, the data indicate that one was apparently at a very slightly lower elevation than the other and the liquid flow rate data for that particular riser are plotted on FIGURE 9.

Example IV The tests of this example, demonstrating the heat transfer ability of our liquid-vapor distribution tray, were conducted in a closed vertical vessel resembling a typical catalytic downfiow reactor. A horizontal distribution tray containing two bubble cap and riser assemblies was located below the feed points. Risers were constructed of As-inch steel tubing, 9% inches tall and 3% inches outside diameter. Risers of this particular length were selected to permit viewing through an available window in the test device. The caps were 4%inch inside diameter standard bubble caps, each having seven slots A-inch wide by 2 /2 inches long, equidistantly spaced around the periphery of the cap. The tray effectively isolated the upper vessel section from the lower vessel section except for the fiow communication through the two bubble cap and riser assemblies.

Partially plugged funnels with Megapack thermocouples were placed below each distributor assembly to create a pool of liquid for temperature measurement. Thermocouples were also installed to read the temperature of the inlet gas and liquid, the outlet gas, and the oil on the tray.

Hot kerosene and cold carbon dioxide were used to simulate liquid and vapor feeds to the reactor. The carbon dioxide entered at the top of the vessel at a rate of 1,470 actual cubic feet per hour. Hot kerosene entered through the side wall just above the distributor tray at a point adjacent the east distributor assembly. The kerosene feed entered at a rate of 32.8 lb./min. System pressure was maintained at 200 p.s.i.g. On achieving steady state conditions, the following temperatures were read:

Inlet gas F 76 Outlet gas F 106 Inlet oil F 122 Oil on tray F 121 Oil below east riser F 112 Oil below west riser F 110 Unexpectedly, although the inlet oil and gas temperature dilference was 46 F., the outlet difference was only 5 F. The calculated heat transfer efliciency amounted to about 89 percent which is quite high when compared with conventional heat exchange systems. This heat transfer efficiency is defined as the percent reduction of the initial difference between oil and gas temperatures toward zero. Other test runs have established that these heat transfer elficiencies are not dependent on the liquid and gas flow rates within normal process operating ranges.

There are many modifications and non-critical features of our invention not specifically referred to herein but within its scope as delineated in the present specification and encompassed by the following claims.

We claim:

1. A process for contacting a liquid and a vapor in a substantially concurrent downflow manner comprising:

passing said liquid and said vapor downwardly through a contacting vessel from an upper section of said vessel to a lower section thereof; distributing said liquid over a substantially horizontal distribution tray, said distribution tray being mounted in said vessel so as to separate said upper section of said vessel from said lower section thereof;

maintaining a shallow reservoir of said liquid on said distribution tray;

contacting said vapor with said liquid in said liquid reservoir so that said liquid is entrained from said liquid reservoir by said vapor; and

transporting all of said vapor containing said entrained liquid upwardly from said reservoir through a plurality of first confined annular paths, then downwardly through a plurality of second confined center paths contained within said first confined annular paths, said vapor and said entrained liquid passing through said distribution tray to said lower section of said vessel.

2. The process of claim 1 wherein said downflowing liquid and vapor pass through a plurality of said substantially horizontal distribution trays located one above the other and spaced apart within said vessel.

3. The process of claim 1 wherein said liquid and said vapor passing downwardly through said contacting vessel to said distribution tray are at substantially different temperatures and wherein the difference in temperature between said vapor and said entrained liquid exiting from said second confined center paths is substantially lower than the difference in temperature of said liquid and said vapor passing downwardly to said distribution tray.

4. A process for contacting a feed mixture of liquid and vapor with a bed of particle-form solids which comprises:

introducing said liquid-vapor mixture into a contacting vessel containing said bed of particle-form solids;

distributing the liquid portion of said liquid-vapor feed mixture on a substantially horizontal distribution tray, said distribution tray located above said bed of particle-form solids and spaced apart therefrom and across the upper face thereof;

maintaining a shallow reservoir of said liquid portion on said distribution tray;

cont-acting the vapor portion of said liquid-vapor feed mixture with said liquid portion in said liquid reservoir so that said liquid portion is entrained from said liquid reservoir by said vapor;

transporting all of said vapor portion containing said entrained liquid portion first upwardly from said reservoir through a plurality of first confined annular paths, then downwardly through a plurality of second confined center paths contained within said first confined annular paths, said vapor portion and said entrained liquid portion passing through said distribution tray and out of contact therewith in such manner that said liquid portion is substantially uniformly distributed over the surface of said bed of particle-form solids;

conducting said uniformly distributed liquid-vapor feed mixture substantially downwardly through said bed of particle-form solids so that said feed mixture is contacted therewith; and withdrawing the product resulting from said contacting of said liquid-vapor feed mixture with said bed of particle-form solids from said contacting vessel.

5. The process of claim 4 in which said liquid and vapor feed comprises hydrocarbons and said particleform solids constitute a hydrocarbon conversion catalyst, said catalyst bed being maintained at hydrocarbon conversion conditions.

6. The process of claim 4 in which said liquid and vapor feed comprises hydrocarbons, and said particleform solids constitute a hydrodesulfurization catalyst, said catalyst bed being maintained at hydrodes-ulfurization conditions.

7. The process of claim 4 in which said liquid and vapor feed comprises hydrocarbons, and said particleform solids constitute a hydrocracking catalyst, said catalyst bed being maintained at hydrocracking condition-s.

8. In combination with a contacting vessel, an apparatus for contacting and uniformly distributing a substantially downfiowing liquid-vapor mixture over the cross-section of said vessel comprising:

a distribution tray substantially horizontally mounted Within said vessel below the source of said liquidvapor mixture, said distribution tray extending across the cross-section of said vessel to separate an upper section of said vessel from a lower section thereof;

a plurality of downcomer conduit means through said distribution tray, said downcomer conduit means being the only fluid communication between said upper section and said lower section through which said liquid-vapor mixture passes, .said downcomer conduit means having their upper edges substantially level; and

a cap surmounting each of said downcomer conduit means and fixedly secured thereto, each of said caps having a peripheral skirt extending downwardly to a level below that of the upper periphery of said downcomer conduit means and to a level above said distribution tray thereby forming an annulus between said peripheral skirt and said downcomer conduit means, said cap and downcomer conduit means serving as the sole conduits defining the flow path of liquid-vapor mixture from said upper section of said vessel to said lower section thereof.

9. The apparatus of claim 8 in which said downcomer conduit means comprise a plurality of cylindrical conduits of substantially equal size extending perpendicularly through said distribution tray.

10. The apparatus of claim 8 in which each cap is substantially uniformly slotted around its skirt.

11. The apparatus of claim 8 in which said downcomer conduit means each have at least one substantially vertical slot extending from said upper periphery of said conduit means downwardly to a terminus intermediate between said upper periphery thereof and said lower periphery of said cap.

12. The apparatus of claim 8 wherein said contacting vessel contains a plurality of said substantially horizontal distribution trays mounted one above the other in said vessel and spaced apart therein.

13. The apparatus of claim 8 including:

a substantially horizontal quench deck mounted in said vessel above said distribution tray and spaced apart therefrom, said quench deck extending across the cross-section of said vessel and having at least two openings therethrough located substantially equidistant from a center axis of said vessel and spaced substantially equidistant about said center axis;

a quench box attached to the under side of said quench deck and supported therefrom, said quench box having side and bottom members and said quench deck servingas a top member of said box, said openings in said quench deck opening into said quench box, and said bottom member of said quench box having at least two openings therethrough located substantially equidistant aboutsaid center axis of said vessel and substantially uniformly offset about said center axis from said openings in said quench deck; and

a perforated tray mounted within said vessel below said quench deck to which said quench box is attached and above said distribution tray, said perforated tray being spaced apart therefrom and extending substantially across a cross-section'of said vessel, said perforated tray having a plurality of relatively small diameter holes located therethrough and substantial ly uniformly disposed over the surface of said perforated tray except for an area immediately beneath said quench box outlet openings.

14. An apparatus for contacting in a substantially downflow manner a liquid-vapor mixture with a bed of particle-form solids comprising in combination:

a vessel containing at least one solids bed extending from a lower to an upper level therein;

an inlet means in said vessel located above said upper level of said solids bed to permit introduction of said liquid-vapor mixture into said vessel above said bed of particle-form solids;

an outlet means in said vesselbelow said bed of particle-form solids; I

a substantially horizontal distribution tray mounted in 16' said vessel between said inlet means and said upper level of said solids bed and extending across the cross-section of said vessel in such manner that said inlet means of said vessel is separated from said particle-form solids bed;

a plurality of downcomer conduit means through said distribution tray, said downcomer conduit means being the only fluid communication between said inlef means and said particle-form solids bed, through which said liquid-vapor mixture passes downwardly onto said solids bed, said downcomer conduit means having their upper edges substantially level;

a cap surmounting each of said downcomer conduit means and fixedly secured thereto, each of said caps having a peripheral skirt extending downwardly to a level below that of the upper periphery of said downcomer conduit means, but above the level of said distribution tray, thereby forming an annulus between said peripheral skirt and said downcomer conduit means, said cap and downcomer conduit means serving as the sole conduits defining the flow path of liquid-vapor mixture through said distribution tray to said particle-form solids bed.

15. The apparatus of claim 14 in which said downcomer conduit means comprise a plurality of cylindrical conduits of substantially equal size extending perpendicularly through said distribution tray.

16. The apparatus of claim 14 in which each cap is substantially uniformly slotted around its skirt.

17. The apparatus of claim 14 in which said particleform solids are contained in a plurality of separate beds, said beds being one above the other and spaced apart within said vessel, each of said beds having a substantially horizontal distribution tray located thereabove and below the next above of said beds.

18. The apparatus of claim 15 in which said downcomer conduit means each have at least onesubstantially vertical slot extending from the upper edge of said conduit means to a terminus intermediate between said upper edge thereof and said lower periphery of said cap.

19. The apparatus of claim 15 in which said cylindrical conduits extend through said distribution tray and below the lower surface thereof a distance not exceeding the diameter of said cylindrical conduit, the portion of said cylindrical conduit extending below said distribution tray increasing in diameter from said lower surface of said distribution tray to the lower extremity of said cylindrical conduit.

20. The apparatus of claim 19 wherein said cylindrical conduits extending below said distribution tray are flared at an angle of between about 10 degrees and about 70 degrees from the axis of said cylindrical conduit.

21. In combination:

a contacting vessel containing a plurality of contacting zones disposed one above the other and spaced apart within said vessel;

at least one intermediate zone within said vessel between an upper of said contacting zones and the next lower of said contacting zones;

at least one intermediate feed means communicating from the exterior of said vessel to at least one of said intermediate zones for adding intermediate liquid or gaseous feeds to a liquid-vapor mixture flowing through said contacting vessel in a substantially downflow manner;

a substantially horizontal quench deck mounted in said intermediate zone of said vessel immediately below said intermediate feed means, said quench deck extending across the cross-section of said vessel and having at least two openings therethrough located substantially equidistant from a center axis of said vessel and spaced substantially equidistant about said center axis;

a quench box attached to the under side of said quench deck and supported therefrom, said quench box hava perforated tray located in said intermediate zone of said vessel below said quench box, said perforated tray extending substantially across a cross-section of said vessel, said perforated tray having a plurality of relatively small diameter holes located therethrough and substantially uniformly disposed over the surface of said perforated tray except for an area immediately beneath said quench box outlet open ings;

a substantially horizontal distribution tray mounted in said intermediate zone of said vessel immediately below and spaced apart from said quench box, and

a plurality of downcomer conduit means through said distribution tray, said downcomer means being the only fluid communication for said downwardly flowing liquid-vapor and intermediate feed mixtures, said downcomer conduit means having their upper edges substantially level; and

cap surmounting each of said downcomer conduit means and fixedly secured thereto, each of said caps having a peripheral skirt extending downwardly to a level below that of the upper periphery of said downcomer conduit means and to a level above said distribution tray, thereby forming an annulus between said peripheral skirt and said downcomer conduit means, said cap and downcomer conduit means serving as the sole conduits defining the flow path of liquid-vapor mixture from said upper section of said vessel to said lower section thereof.

References Cited by the Examiner UNITED STATES PATENTS 7/1949 Cummings 2O8l46 immediately above and spaced apart from the next 11/1963 Young et a1 208 213 lower of said contacting zones, said distribution tray extending across the cross-section of said vessel; ALPHONSO D. SULLIVAN, Primary Examiner. 

4. A PROCESS FOR CONTACTING A FEED MIXTURE OF LIQUID AND VAPOR WITH A BED OF PARTICLE-FORM SOLIDS WHICH COMPRISES: INTRODUCING SAID LIQUID-VAPOR MIXTURE INTO A CONTACTING VESSEL CONTAINING SAID BED OF PARTICLE-FORM SOLIDS; DISTRIBUTING THE LIQUID PORTION OF SAID LIQUID-VAPOR FEED MIXTURE ON A SUBSTANTIALLY HORIZONTAL DISTRIBUTION TRAY, SAID DISTRIBUTION TRAY LOCATED ABOVE SAID BED OF PARTICLE-FORM SOLIDS AND SPACED APART THEREFROM AND ACROSS THE UPPER FACE THEREOF; MAINTAINING A SHALLOW RESERVOIR OF SAID LIQUID PORTION ON SAID DISTRIBUTION TRAY; CONTACTING THE VAPOR PORTION OF SAID LIQUID-VAPOR FEED MIXTURE WITH SAID LIQUID PORTION IN SAID LIQUID RESERVOIR SO THAT SAID LIQUID PORTION IS ENTRAINED FROM SAID LIQUID RESERVOIR BY SAID VAPOR; TRANSPORTING ALL OF SAID PORTION CONTAINING SAID ENTRAINED LIQUID PORTION FIRST UPWARDLY FROM SAID RESERVOIR THROUGH A PLURALITY OF FIRST CONFINED ANNULAR PATHS, THEN DOWNWARDLY THROUGH A PLURALITY OF SECOND CONFINED CENTER PATHS CONTAINED WITHIN SAID FIRST CONFINED ANNUALR PATHS, SAID VAPOR PORTION AND SAID ENTRAINED LIQUID PORTION PASSING THROUGH SAID DISTRIBUTION TRAY AND OUT OF CONTACT THEREWITH IN SUCH MANNER THAT SAID LIQUID PORTION IS SUBSTANTIALLY UNIFORMLY DISTRIBUTED OVER THE SURFACE OF SAID BED OF PARTICLE-FORM SOLIDS; CONDUCTING SAID UNIFORMLY DISTRIBUTED LIQUID-VAPOR FEED MIXTURE SUBSTANTIALLY DOWNWARDLY THROUGH SAID BED OF PARTICLE-FORM SOLIS SO THAT SAID FEED MIXTURE IS CONTACTED THEREWITH; AND WITHDRAWING THE PRODUCT RESULTING FROM SAID CONTACTING OF SAID LIQUID-VAPOR FEED MIXTURE WITH SAID BED OF PARTICLE-FORM SOLIDS FROM SAID CONTACTING VESSEL.
 7. THE PROCESS OF CLAIM 4 IN WHICH SAID LIQUID AND VAPOR FEED COMPRISES HYDROCARBONS, AND SAID PARTICLEFORM SOLIDS CONSTITUTE A HYDROCRACKING CATALYST, SAID CATALYST BE BEING MAINTAINED AT HYDROCARCKING CONDITIONS. 